Allow ProxyService to share URLRequestContext with everything else.

net/proxy/dhcp_proxy_script_fetcher_win.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
 #define NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_
 
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 26 matching lines @@
   // Creates a DhcpProxyScriptFetcherWin that issues requests through
   // |url_request_context|. |url_request_context| must remain valid for
   // the lifetime of DhcpProxyScriptFetcherWin.
   explicit DhcpProxyScriptFetcherWin(URLRequestContext* url_request_context);
   ~DhcpProxyScriptFetcherWin() override;
 
   // DhcpProxyScriptFetcher implementation.
   int Fetch(base::string16* utf16_text,
             const CompletionCallback& callback) override;
   void Cancel() override;
+  void OnShutdown() override;
   const GURL& GetPacURL() const override;
   std::string GetFetcherName() const override;
 
   // Sets |adapter_names| to contain the name of each network adapter on
   // this machine that has DHCP enabled and is not a loop-back adapter. Returns
   // false on error.
   static bool GetCandidateAdapterNames(std::set<std::string>* adapter_names);
 
  protected:
   int num_pending_fetchers() const;
@@ skipping 101 matching lines @@
 
   // Pointer to string we will write results to. Not valid in states
   // START and DONE.
   base::string16* destination_string_;
 
   // PAC URL retrieved from DHCP, if any. Valid only in state STATE_DONE.
   GURL pac_url_;
 
   base::OneShotTimer wait_timer_;
 
-  URLRequestContext* const url_request_context_;
+  // Set to nullptr on cancellation.
+  URLRequestContext* url_request_context_;
 
   // NULL or the AdapterQuery currently in flight.
   scoped_refptr<AdapterQuery> last_query_;
 
   // Time |Fetch()| was last called, 0 if never.
   base::TimeTicks fetch_start_time_;
 
   // Worker pool we use for all DHCP lookup tasks.
   scoped_refptr<base::SequencedWorkerPool> worker_pool_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(DhcpProxyScriptFetcherWin);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_DHCP_PROXY_SCRIPT_FETCHER_WIN_H_